The fabrication of semiconductor devices, such as logic and memory devices, typically includes processing a semiconductor device using a large number of semiconductor fabrication and metrology processes to form various features and multiple layers of the semiconductor devices. Select fabrication processes utilize photomasks/reticles to print features on a semiconductor device such as a wafer. As semiconductor devices become smaller and smaller laterally and extended vertically, it becomes critical to develop enhanced inspection and review devices and procedures to increase sensitivity and throughput of photomask/reticle and wafer inspection processes.
Semiconductor devices may develop defects during the fabrication processes. Inspection processes are performed at various steps during a semiconductor manufacturing process to detect defects on a specimen. Inspection processes are an important part of fabricating semiconductor devices such as integrated circuits. These inspection processes become even more important to successfully manufacture acceptable semiconductor devices as the dimensions of semiconductor devices decrease. Detection of defects has become highly desirable as the dimensions of semiconductor devices decrease, as even relatively small defects may cause unwanted aberrations in the semiconductor devices.
One inspection technology includes electron beam based inspection such as scanning electron microscopy (SEM). In some instances, scanning electron microscopy is performed via secondary electron beam collection (e.g., a secondary electron (SE) imaging system). In other instances, scanning electron microscopy is performed by splitting a single electron beam into numerous beams and utilizing a single electron-optical column to individually tune and scan the numerous beams (e.g., a multi-beam SEM system). In other instances, scanning electron microscopy is performed via an SEM system which includes an increased number of electron-optical columns (e.g., a multi-column SEM system).
In a multi-column SEM system, the smaller the portion of the full field area covered by a particular electron-optical column, the greater the total overlap that is necessary to stitch the images gathered from each electron-optical column back together. In addition, a multi-column SEM system may not include the capability to scan both a photomask/reticle and a wafer. Further, the total time a multi-column SEM system requires for high resolution characterization of a photomask/reticle or wafer is dependent on the number of, and spacing between, the multiple electron-optical columns. For example, the amount of time required for inspection of the full field area is increased if the multiple electron-optical columns are spaced such that the total inspection area of all columns is larger than the full field area of the photomask/reticle, as the columns within the field area have to inspect more surface area to make up for the non-inspecting columns outside the field area. By way of another example, depending on surrounding material of the SEM system, the surface of a photomask/reticle or wafer may be charged due to exposure of electron-optical columns outside of the photomask/reticle or wafer full field, which may in turn interfere with adjacent, in-field electron-optical columns.
Therefore, it would be advantageous to provide a system and method that cures the shortcomings described above.